Airplane landing gear



AIRPLANE LANDING GEAR v Filed June 10, 1941 v 2 Sheets-Sheet 1 lNVENTOR 020,420 M imam/v r ATT NEYS Y July 6, 1943. E M BERT AN 2,323,367

AIRPLANE LANDING GEAR Filed June 10, 1941 2 Sheets-Sheet 2 IN'VENTQR Patented July 6, 1943 UNITED STATES PATENTZOFFICEQ i i i 2,323,367

p v AIRPLANE LANDING G EAR' Edward M. Bertran, Jackson Heights, N. Y., as- I signorto Brewster Aeronautical Corporation.

Long Island City, Y. V n v Application June 10, 1941, Serial No. 397,429

reams; (omit-192 This invention relates to aircraft and more particularly to retractable" landing gear devices therefor. V

One of the objectsof the invention i to provide an improved airplane undercarriage which is completely retractable within'the wing panels port the airplane when grounded in an-improved 'mannner.

Otherobjects andadvantages of the invention will appear from the specification hereinafter. I Y In the drawings:

Fig. 1 is afragmentary plan of an airplane showing an undercarriage unit of the'invention,

in its extended position; g

Fig. 2 is a fragmentary front elevationcorrespondingtoFig.1; 7i

Fig. 3 is a fragmentary view, on an enlarged scale, of a detail of Fig. 2; v

'- Fig. 4 is a view similar to that of Fig. i, but showing the landing gear in retracted position within the adjacent wing panel structure; and

Fig. 5 is a fragmentary front elevation correspondingtoFig.4.

The drawings illustrate the invention in *connection with an airplane illustrated fragmentarily as including a fuselage portion I 0 anda win panel l2 extending laterally therefrom. A landing wheel l4 and its retractable supporting gear unit is illustrated as being mounted upon the wing panel l2 to provide one half of a dual wheel landing gear for the airplane; it being understood that a similar unit will be'provided in conjunction with the opposite wing panel to complete the under carriage for the forward end of the airplane. It will also be understood that the mechanisms for effecting extension-retraction movements of the opposite gear units will be preferably so arranged as to procure simultaneous movements thereof in response to pilot manipulation of a single control device in accord with usual practice; but in the interest of simplifying the present specification. and avoiding unnecessary duplication of description of the mechanism and the operation thereof, the drawings and detailed description herein are limited to relate to only one of the undercarriage units.

The landing wheel I4 is rotatably carried by a bearing shaft I 6 extending from the lower end of ashock absorbing main strut l8 which is arranged to bedisposedsubstantiallyvertically when the gear is in extended position, asillustrated in Figs. lam-1'2. Opposite bosses 2U extend'forwardlyand rearwardly from the upper end of the strut l8'into sliding'engagement within'corresponding track devices 22 which are arranged in parallel relation and rigidly mounted upon structural elements of the wingpanel- 12. The tracks 22 are provided with dwell portions 23 (Fig. 3) adapted to engage the bosses 20 when the gear is in' extended position, in such manner as to resistaccidental displacementof the bosses from gear-extended position. The tracks -22 extend laterallyirorn the positions of the dwells toward the wing tipfor guiding movements of the upper end portion of' the strut 18 during retraction of the gear, as will b explained hereinafter. 1

The strut I8 is braced adjacent its lowerend by meansof a pair of diverging brace struts 30-32 which pivotally connect at their .upper ends by' means of aligned bearings 34-36, respectively, to'structural elements ofthe wing panel l2. At their lower ends the brace struts 33-32 connect through means of knuckle joints 38-39, respectively, with the base portion of an A-frame truss defined by struts 40-42-45 which is hinged at 43 to the strut l8'and projects therefrom in plan-view diverging relation and in planview alignment with the brace struts 30-32. The

hinge axes'iof the knuckle points 38-39 are arranged to align in parallelism with the line of the axes of the pivotal connections 34-36 between the bracing struts 30-32 and the wing panel structure.

A crank arm (Fig; 2) is provided to extend rigidly from the upper end portion of the brace strut 3|] beyond the axis of the pivotal connection 34 thereof; and an expansion-contraction strut 52, which may be in the form of a hydraulic jack, is pivotally connected at one of its ends to the crank 50, as at 54. The strut 52 is pivotally connected at its other end, as at 56, to a crank portion 58 which extends upwardly from the wheel strut 18 above the position of the bosses 20-20.

Thus, it will be understood that upon exten-' sion of the strut 52 from the condition thereof illustrated in Figs. 1 and 2, as by introduc-.

'tion of fluid under pressure into the cylinder of the strut 52, pressure forces will be exerted against the crank devices 50-58 in such manner as to cause the upper end of the strut l8 to be moved toward the outer tip end of the wing panel, while the brace strut 30 will be si- 4 and 5. Upon reverse application of fluid pressure within the Jack strut 52 the gear will unfold from the position of Figs. 4 and 5 and return to the position of Figs. 1-3, with some assistance by the forces of gravity.

Thus, it will be understood that the gear of the invention comprises essentially a pair of converging brace struts (30-32) which ar based at relatively widely separated points upon the wing panel in close proximity to .the airplane fuselage where the wing panel framing structure is strongest, and a main strut (l8) which extends vertically from the region of pivotal connection .with the lower converging end portions of the brace struts into vertically abutting connection with the track elements (22). The expansioncontraction strut connects between lever arm portions extending from the upper ends of the main strut and one of the brace struts. Thus, the hydraulic jack mechanism is at all times completely enclosed within the wingcontour and has one of its ends disposed at all times in close proximity to the fuselage of the airplane, whereby the hydraulic pressure conveying conduit devices leading from the fuselage are relatively shortand close coupled. Consequently, when in extended position, the landing wheel II is supported by, means of a pyramidal truss having three widely spaced points of connection to the wind structure; and yet upon retractionflof the gear; thebrace struts (3032) fold so as. to permit the'rigid main strut to be disposed' completely withinfthe i wing contour without requiring provision'of, an

undue amount of space for the retracted gear within the wing panel.

Although, only one form of theinvention has been shown and described in detail, it will be apparent to those skilled in-the' art that the invention is not so limited but that various changes may be made therein without'departing from the spirit of the invention or the scope of the appended claims.

,I claim:

1. In an aircraft, a retractable undercarriage comprising a rigid main strut, landing surface contact means mounted upon one end portion of said main strut, slide-pivot connection means carried by said main strut adjacent its opposite end portion,- track means mounted upon a fixed portion of said aircraft in registry with said connection means and extending in substantially horizontal directions whereby said main strut is adapted to simultaneously slide and pivot at said' opposite end portion thereof relative to said track means for swinging said strut and landing surface contact means into retracted position relative to said aircraft, a pair of diagonally disposed knuckle struts pivotally connected at corresponding end portions thereof to said support strut at positions thereon offset from the position of said slide-pivot connection means and extending therefrom in diverging relation into pivotal connections at their corresponding opposite ends with fixed portions of said aircraft, a crank extending from one of said knuckle struts, a second crank extendingv from said main strut, a beam extending between said knuckle struts at similar sides of the axis of breaking thereof to synchronize their knuckle actionsyand jack means extendin between said cranks for simultaneous actuation thereof.

2. In anaircraft, a retractable undercarriage including a main support strut adapted to extend vertically below said aircraft when in undercarriage-extended condition, a pair of brace struts pivotally connected tov said main strut so as to extend therefrom into pivotal connections withfixed portions of said airplane at widely spaced positions thereon, said brace struts being hinged -intermediately of their ends and adapted to fold for retraction-of said gear, a crank arm extending from the inner end of said main strut,'slide and pivot connection means disposed intermedi- EDWARD M. BER'I'RAN. 

